Software Engineering Institute

February 10, 2025—The way software is expected to perform does not always match the way it runs in production. Before installing software, system owners should assess its risks and impacts on their computing environment. Manual testing of the functional, operational, and security aspects of the software’s execution can yield results of varying accuracy and consistency, depending on the tester’s skill. The Software Engineering Institute (SEI) recently released Silent Sentinel, an open source tool that streamlines and automates software deployment risk analysis. The tool provides a repeatable, consistent process for software teams doing development, quality assurance, infrastructure maintenance, and cybersecurity.

Silent Sentinel is an open source combination of a software profiler and dynamic analysis tools. It uses a Linux-based, containerized sandbox environment to run a series of tests on presumed trustworthy applications written in any language. Users configure the tests for conditions of interest in their deployment environment, such as system calls, memory usage, and network configurations. The tool produces a PDF report, which users can pair with the tool’s interpretation guide to explain the reported data. With this information, system stakeholders can get a realistic assessment of how the application will affect their environment.

“Applications often comprise a suite of frameworks or third-party libraries that don't always include the full source code. Without the source code, I can't necessarily run static analysis tools that may reveal certain vulnerabilities or behaviors, or the number of libraries and frameworks that the application has to interact with,” said Vanessa Jackson, an SEI senior engineer on the Silent Sentinel team. “Stress testing the application within a controlled environment gives developers and consumers of software a better understanding of the risks of deploying an application within an environment.”

By automating risk analysis, Silent Sentinel creates a unified set of baseline data that teams can repeatedly reference, update, and use for evaluating proposed changes.

The benefit could be especially large for the Department of Defense (DoD) as it modernizes its IT systems. The DoD’s Software Modernization Strategy calls for greater adoption of DevSecOps tooling, cyber survivability, and testing. Silent Sentinel could give DoD development teams and their contractors insight into the behavior of their application before a final deliverable is released. Additionally, because the tool easily integrates into a DevSecOps pipeline, teams can get continuous feedback and build risk assessment profiles of their application over time. Product and system owners can have more information on system cyber risk and resilience before accepting delivery, and testers would get pre-deployment data to inform their testing designs.

Software vendors outside the DoD stand to benefit as well. If enough software developers and cybersecurity practitioners build application risk assessment profiles, end users will get a clearer picture of what to expect when integrating external frameworks or libraries into custom code or deploying commercial software onto their infrastructure. “The long-term hope is that software consumers will develop a more security-focused perspective about the software and devices that we all depend on each day,” said Jackson.

Jackson and her SEI colleagues encourage users to download Silent Sentinel from the SEI’s GitHub site, test it out, and provide feedback, either via GitHub or by emailing silent-sentinel@sei.cmu.edu. Those interested in learning more can email the team at the same address or read the Silent Sentinel fact sheet.